Exchange 2013 Edge - Sender Reputation Configuration

Hello together,

The Egde Sender reputation checks seems to be very powerful. Exchange checks the sending server via a proxy.

The part, Exchange communication to proxy, is pretty clear for me and easy to configure.

... But I cannot find information what services the proxy need to provide.

For the communication proxy to internet sending system, what ports the firewall need to open?

What is the communication flow? The edge contact the proxy via port 80. The proxy contact to the sending system on port 80 and test if can send a mail with port 25 back to the edge?

Thanks a lot for your help

Best regards

Thomas